The invention relates to a method for the pressure regulation of a barrier fluid in a pumping device in accordance with the pre-characterising part of the claims herein and a pumping device for a method of this kind in accordance with the pre-characterising part of the claims herein.
Pumping devices for pumping media such as fluids for example, as a rule include a pump unit with a shaft and with a pump housing and a drive unit which is mechanically coupled to the pump unit and also a shaft sealing arrangement which seals the pump housing relative to the shaft. High demands are made on the shaft sealing arrangement if the pump unit and the drive unit are arranged in a common housing or pressure container. Serious damage can arise at the pumping device if the pumping medium which, depending on the use, can also contain solid material components, contaminates critical parts such as bearings. In a case such as this the entire pumping device may often have to be over-hauled. For this reason the common housing or the pressure container is normally filled with a barrier fluid and a pressure regulating system ensures that the pressure of the barrier fluid in the housing or in the pressure container is higher than the pressure of the pumping medium in the pump unit in order to avoid the pumping medium from escaping into the housing or into the pressure container.
In current pressure regulating systems such as those used in underwater pumping devices for crude oil, either pressure/volume compensators are used or electro-hydraulic pressure valves. The use of pressure/volume compensators results in a comparatively complicated pressure regulating system with a correspondingly large number of components and connections. Furthermore, pressure/volume compensators contain elastic partition walls which are vulnerable to material fatigue. If electro-hydraulic pressure valves are used, an electronic pressure sensor and control is necessary and delays in the reaction time of the pressure regulation system result.